Hand-Arm Vibration Syndrome

A guide to the problem of Hand-Arm Vibration (White Finger)

HAVS - The Problem

Hand-Arm Vibration Syndrome (HAVS) is a widespread industrial disease affecting tens of thousands of workers. Its best known effect is vibration-induced white finger (VWF)
Attacks are painful and can result in the loss of ability to grip properly (severe cases can lead to gangrene)
Any vibrating tool or process which causes tingling or numbness after 5 to 10 minutes of continuous use is suspect
Where people regularly use such equipment for prolonged periods there is likely to be a risk of injury
Construction workers are often exposed to high-risk machines like Plate Compactors, Petrol Saws, Breakers, and other common power tools.

What is hand-arm vibration?		Hand-arm vibration syndrome (HAVS) is a widespread industrial disease affecting hundreds of thousands of workers. It is caused by regular exposure to vibration, especially from vibrating hand tools, and is therefore a particular problem for the construction industry.

Exposure to hand-arm vibration can cause:		damage to the blood vessels, reducing the blood supply damage to nerves, causing a permanent loss of feeling damage to bones and muscles, similar to arthritis Symptoms include: tingling and numbness loss of sensation and manual dexterity finger blanching and chilblains, aching digits and limbs. Its best-known effect is vibration white finger (VWF), where the fingers turn white during an attack, but it is the loss of manual dexterity and grip strength which are the most debilitating symptoms.

Measuring hand-arm vibration		Hand-arm vibration is notoriously difficult to measure. The main pitfalls are associated with the necessity to attach the transducers directly to the plant or component, and the main factor affecting the accuracy of an assessment is the skill and experience applied to the measurements. Full assessments including both measurements and dose calculations should only be carried out by a 'competent person'. Most importantly, vibration measurements should not be carried out using hand-held accelerometers, unless there is absolutely no alternative. The assessment procedure (to BS 6842:1987) involves: carrying out 3-axis (on two or three handles for many tools) frequency weighted measurements on each tool handle during typical 'real' tool use an accurate assessment of "finger on trigger" time calculation of the vibration dose for each handle and operation A database of accurate field vibration measurements is available for many hand tools, which can be used as part of a risk assessment.

(Extract from Construction News 19/04/2001)

General legislation including the Health and Safety at Work Act 1992 and the Management of Health and Safety at Work Regulations 1992 require that:

EMPLOYERS NEED TO CONTROL THE RISK OF HAVS

HAVS - The Solution

Include Hand-Arm Vibration in your Health and Safety policy:

Train operatives
Monitor and limit exposure
Select low vibration equipment

Check that the vibration levels and useage times quoted by the manufacturer are accurate and represent real life working conditions.
Ensure the machine’s productivity (output) is high. Inefficient equipment, even with low vibration, can expose operators to harmful levels because they have to use it for longer to finish the job.
Choose tools that are easy and comfortable for operators to use. Less effort equals less vibration.

Belle Group equipment is built for low vibration

Tested under realistic working conditions

Designed for maximum performance and output

Comfortable to use with excellent ergonomics

HAVS - The Proof

Comparative tests were carried out by AV Technology (Stockport) Ltd April 2001.

The information gathered was to be used in a publication "Plant Hire Executive" to demonstrate the difference in the data supplied by manufacturers and the actual levels produced under working conditions.

Tests were carried out on 100mm deep MOT material (crushed aggregate with fines). Summarised below are the average levels of the 6 passes for each compactor.


Average a_h,_w		Time Limit

Belle PC 400	3.88m/s²	4h 10min

Competitor A	8.97m/s²	47min

Competitor B	12.15m/s²	25min

Competitor C	9.24m/s²	44min

Belle PC 400 (second set to establish repeatability)	3.69m/s²	4h 36min

The instrumentation used to perform the measurements was a Svan 912AE Sound and Vibration Analyser, Svan 06A 4 channel module and Svan AP5021 Hand-Arm Adapter Set. Before leaving AVT's offices the instrumentation was calibrated using a Bruel & Kjaer Type 4291 Calibrator which itself is traceably calibrated to UKAS (formally NAMAS) Standards.

The analyser was set-up to measure weighted acceleration magnitudes in all three axes simultaneously.The tri-axial accelerometer was fitted to the handle of each compactor at the position where the operator normally holds the hand by means of a jubilee clip. The weighting curve used corresponds with the hand-arm vibration weighting curve in BS 6842:1987. Handarm vibration was measured in 3 axes simultaneously through several work cycles of approximately 22 seconds each and the total weighted rms acceleration was determined from the vector sum of the three weighted rms acceleration values ('a_x,_w' side to side, 'a_y,_w' fore and aft, and 'a_z,_w' vertical).

Each compactor was tested running over a 'MOT' type material. The ground was 'raked' by means of an adaptor fitted on to the front of a skid steer loader after each machine to provide an identical work surface for all compactors. A total of 6 passes were undertaken on the same section of track on each compactor.

Belle Group plate compactors are designed to give the lowest hand-arm vibration and the maximum performance AS STANDARD

Dual Force is available on all PC Plates to upgrade the compaction force - full compaction is achieved with fewer passes so the operator is exposed to less vibration

Belle Group AFS Floor Saws have been developed to give the lowest hand-arm vibration and the maximum performance

The use of hand held saws for floor sawing is an extremely high risk operation even for small patches. The AFS300 is the perfect alternative, the 350 gives a deeper cut and higher output.

Belle Group UD Breakers have been developed to give the lowest hand-arm vibration and the maximum performance

Breakers are often used for extended periods so operators are at high risk. The unique design of the UD breaker maximises operator control and vibration reduction.